This invention relates to the art of papermaking and more particularly to an apparatus and method of treating paper pulp stock. Paper pulp of relatively low consistency (3 to 8% fiber content) has been fed to a refiner, such as a disc refiner. There, the individual fibers of the pulp stock slurry are cut and/or fractured so as to render the stock suitable for papermaking.
For the purpose of increasing the efficiency of such papermaking operations, it is desirable to treat pulp by a disc refiner having a higher fiber content, such as a fiber content of from 8 to 15%. However, such attempts have usually failed because this higher fiber content results in a jamming or clogging of the disc refiner. Once the refiner commences to clog, finally clogging occurs shortly thereafter with the result that the disc refiner is no longer operable. In attempting to feed medium pulp consistencies to a disc refiner, such as pulp stock having a fiber content of from 8 to 15%, flocculation of the fibers with the slurry causes the above described clogging of the disc refiner.
Prior to this invention, mechanical devices for fluidizing medium consistency paper stock had been known. Such devices include a fluidizing device sold by Kamyr, Inc. under the brand name MC Pump, and is characterized by the seller as a centrifugal, thick-stock pump. This is a rotary device for de-flocculating paper pulp. Such devices have previously been useful, for example, in pumps for pumping paper stock of medium consistency from a storage tank to another portion of the papermaking system. It has been found that medium consistency pulp exhibits high pipe-clogging characteristics and a fluidizer, such as the Kaymr MC Pump, serves to de-flocculate the medium consistency pulp in a pulp storage tank or chest, to thereby enable it to be passed in hydraulic conduits without clogging.